/////////////////////////////////////////////////////////////////////////////
// Original code from libhdfs3. Copyright (c) 2013 - 2014, Pivotal Inc.
// All rights reserved. Author: Zhanwei Wang
/////////////////////////////////////////////////////////////////////////////
//  Modifications by Kumo Inc.
// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//



#pragma once


#include <kmhdfs/client/file_system.h>
#include <kmhdfs/server/located_blocks.h>

namespace Hdfs {
namespace Internal {
class InputStreamInter;
}

/**
 * A input stream used read data from hdfs.
 */
class InputStream {
public:
    InputStream();
    InputStream(std::shared_ptr<Internal::LocatedBlocks> lbs);
    
    ~InputStream();

    /**
     * Open a file to read
     * @param fs hdfs file system.
     * @param path the file to be read.
     * @param verifyChecksum verify the checksum.
     */
    void open(FileSystem & fs, const char * path, bool verifyChecksum = true);

    /**
     * To read data from hdfs.
     * @param buf the buffer used to filled.
     * @param size buffer size.
     * @return return the number of bytes filled in the buffer, it may less than size.
     */
    int32_t read(char * buf, int32_t size);

    /**
    * To read data from hdfs.
    * @param buf the buffer used to filled.
    * @param size buffer size.
    * @param position the position to seek.
    * @return return the number of bytes filled in the buffer, it may less than size.
    */
    int32_t pread(char * buf, int32_t size, int64_t position);

    /**
     * To read data from hdfs, block until get the given size of bytes.
     * @param buf the buffer used to filled.
     * @param size the number of bytes to be read.
     */
    void readFully(char * buf, int64_t size);

    /**
     * Get how many bytes can be read without blocking.
     * @return The number of bytes can be read without blocking.
     */
    int64_t available();

    /**
     * To move the file point to the given position.
     * @param pos the given position.
     */
    void seek(int64_t pos);

    /**
     * To get the current file point position.
     * @return the position of current file point.
     */
    int64_t tell();

    /**
     * Close the stream.
     */
    void close();

private:
    Internal::InputStreamInter * impl;
};

}
